Inference
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StepFun

Step 3.5 Flash

Step 3.5 Flash is a standard model from StepFun. It has 3 scored results in 2 categories. It has no index.

  • Open weights
  • Standard
  • Input: text
  • Released 2026-02
UnrankedEnough results for an index.
IndexAll categories, out of 100.UnrankedMedian 51.0
CoverageIndex weight that has results.30%
SpeedOutput tokens per second.42/sMedian 67/s
First tokenSeconds to the first output token.1.0 sMedian 1.3 s
Input / 1MUS dollars per 1M input tokens.$0.10Median $0.60
Output / 1MUS dollars per 1M output tokens.$0.30Median $2.55
ContextMaximum tokens in one request.262KMedian 262K
EloLMArena rating and rank.1403±4 #154Median 1422

Details

From OpenRouter
API IDThe model ID on OpenRouter.
stepfun/step-3.5-flash
Max outputMaximum output tokens per request.
66K
Knowledge cutoffLast date of training data.
—
ToolsTool calls on OpenRouter.
Yes
JSON outputOutput follows a given JSON schema.
No
Cache read / 1MUS dollars per 1M cached tokens.
—
WeightsLink to the published weights.
Hugging Face (opens in a new tab) ↗
RetiresDate OpenRouter removes the model.
—

Where to run

APIs that serve this model.
3 providers
ProviderTypeMaker, cloud, host or router.InputOutputContext
OpenRouterRouter$0.10$0.30262K
SiliconFlowHost$0.10$0.30262K
StepFunMaker$0.10$0.30256K

US dollars per 1M tokens, list price. From models.dev (opens in a new tab) (MIT).

Capabilities

Index per category, out of 100.
Out of 100
AgenticMulti-step tasks with tools.None counted——
CodingCode writing and repair.2 counted55.7—
ReasoningLogic problems and puzzles.None counted——
MultimodalTasks with images and text.None counted——
KnowledgeFacts and expert knowledge.None counted——
MultilingualTasks in many languages.None counted——
InstructionTasks with strict prompt rules.None counted——
MathMath problems.1 counted51.8—

Results

3 counted
BenchmarkThe benchmark name.ResultThe score from the source.PlacePlace among results on this benchmark.
American Invitational Mathematics Examination 2025Math97.3%3 / 53
LiveCodeBench v6Coding86.4%18 / 59
Software Engineering Benchmark VerifiedCoding74.4%48 / 114

Sources

BenchLMCC BY-NC 4.0OpenRouterTerms restrict reusemodels.devMIT

History

5 releases
Output / 1M$0.30 → $0.30
23 Oct 202612 Nov 2026

Questions

How much does Step 3.5 Flash cost?
$0.10 per 1M input tokens, $0.30 per 1M output tokens.
How fast is Step 3.5 Flash?
42 output tokens per second, 1.0 s to the first token.
What is the context window of Step 3.5 Flash?
262K tokens.
Is Step 3.5 Flash open source?
Yes. Its weights are published.
When was Step 3.5 Flash released?
February 2026.

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